exxos's Atari, Amiga & retro forum

That's good news. Replacing 1990s surface mount capacitors is a must. They're just too dangerous to leave on a board. I don't know if the designs got any better by the end of the decade or not.

alexh wrote: 29 May 2022 19:53 Lucky that fixed it. (Or experience?) Anyhow nice read. Good to see your going again

I do confess, a bit of luck involved, I was going to replace them later but figured 'what the hell I'll do it now, nothing to lose'.

Given it looked like memory problems, and the cap with the lifted pad, C160, is part of the filtered supply to the DRAM, it seemed logical.

I think there's always an element of luck with machines like these.

stephen_usher wrote: 29 May 2022 20:09 That's good news. Replacing 1990s surface mount capacitors is a must. They're just too dangerous to leave on a board. I don't know if the designs got any better by the end of the decade or not.

Yeah, certainly is good news and a must to replace them. I've since discovered that there are 2 more of those caps over in the audio out circuit and looking leaky. They'll be getting replaced ASAP.

Well done RJ. I’ve got some of those caps to replace on an a1200, what method did you use for removal?

PhilC wrote: 30 May 2022 08:23 Well done RJ. I’ve got some of those caps to replace on an a1200, what method did you use for removal?

@PhilC I need to do the same with my A1200 so @rubber_jonnie any tips on removal would be helpful.

@PhilC let me know where you end up sourcing the replacements from.

@Icky @PhilC

I personally tend to use the 'Mr Carlson' & 'Adrian Black' method, which involves twisting the can horizontally as shown here: https://www.youtube.com/watch?v=X8N9O3a9jiM

Desoldering of these SMD caps is difficult at best, especially if the caps have leaked over the pads/solder, and the connections to the can are generally speaking more fragile than the pads. Once the can is off you have access to the terminals and it's much easier to heat the lead to remove it gently.

I know this is a controversial method, but it works for me and the only time I've had pads come away is when they've already been corroded.

I got my A1200 capacitor kit from here: https://amigakit.amiga.store/a1200-capa ... rrency=GBP

Just arrived, 20mm steel and 20mm Delrin balls to try in the mouse.


They both fit perfectly, but slip on the rollers. Of both, the Delrin ball seems much more like the real thing, but the steel ball gives the mouse a nice weight.

I just need a way to give the rollers more grip and I think either is going to work well as a replacement.

In other A5000 news, I managed to get the FDD to format a disk in 360K Atari last night, and was able to extract the IDE formatting tool, but sadly it didn't work, in that the drive was not detected :(

Then this morning, the floppy died, though at least it still boots to the desktop thats in ROM. I expect it is slowly failing traces, so I'll have to buzz it out again.

I also removed the last two leaky SMD dustbin caps, and it was clearly affecting the sound, as I now get a beep on boot, which is new.

I also tried in the Econet adapter and that works too and is detected on boot, though it makes the clock jump forward an hour.

It's going to be a long haul I think, but I like a challenge.

Not sure if this is connected, but since I removed the last two 47uF leaky dustbins from the audio circuit, I now also have my FDD back...

I also have decided that the Delrin ball, despite being the most original looking, is too light to do the job, even though on a mouse mat like surface it does seem to rotate ok, so I'm likely going to run with the steel ball.

I've ordered some silicone tubing that will fit nicely over the x/y rollers and should provide a decent grip for the ball, and there is enough of a gap once the ball is in place to allow for the thickness of the tube n the rollers.

Let's see how that goes :)

Have you tried scuffing the surface of the balls using sand paper?

stephen_usher wrote: 30 May 2022 13:23 Have you tried scuffing the surface of the balls using sand paper?

I haven't yet, however the internal X/Y rollers are shiny smooth and whilst it would no doubt help to sand the surface of the balls, I'm not sure how effective it would be given the surface of the rollers, hence why I want to add thin rubber to the x/y rollers.

The original ball looks to be like most mouse balls and has a rubber like surface.

The Delrin ball would be perfect if it was just a smidge heavier.